JPH06188522A - Heat sink and semiconductor laser - Google Patents

Abstract

PURPOSE:To allow downsizing of semiconductor laser by facilitating the angular alignment of a semiconductor laser chip. CONSTITUTION:A heat sink 2 is made of a semiconductor material such as silicon and a PN junction plane 9 is provided internally. Upper face for mounting a semiconductor laser chip 1 has a step structure comprising an upper stage face to be provided with a heat sink upper electrode 8 and a lower stage face to be provided with a heat sink upper electrode 6 wherein a normal mesa inclining face 14 is provided at the border part of upper and lower stage faces. The monitor light emitting edge of the semiconductor laser chip 1 abuts, at the lower side thereof, on the inclining face 14 and the semiconductor laser chip 1 is bonded to the surface of the upper electrode 6 thus conducting angular alignment between the semiconductor laser chip 1 and the heat sink 2. The heat sink 2 functions as a photodiode incorporating a PN junction 9. Monitor light impinging on the inclining face 14 defracts to arrive at the PN junction 9. Monitor light reflected on the inclining face 14 does not return back to the active layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink for dissipating heat of a semiconductor laser chip, and a semiconductor laser device for dissipating heat by the heat sink and having a laser beam detecting function for monitoring the output of the semiconductor laser chip. Regarding

[0002]

2. Description of the Related Art A conventional laser device of this kind is shown in FIGS. 6 and 7 in a side view and a plan view, respectively. This laser device includes a semiconductor laser chip 1, a heat sink 2,
It is composed of a photodiode 18 and a submount 19. The semiconductor laser chip 1 is mounted on the heat sink 2, and the heat sink 2 and the photodiode 18 are mounted on the submount 1
It is mounted on the 9. The heat generated by the semiconductor laser chip 1 is transferred to the heat sink 2, and the heat of the heat sink 2 is dissipated to the submount 19. Laser light emitted rearward from the active layer 3 of the semiconductor laser chip 1 is monitor light 15, and light emitted frontward is output light 21. The monitor light 15 is converted into a current by the photodiode 18, and the power of the output light 21 can be estimated by measuring this current. A part of the monitor light 15 is reflected by the surface of the photodiode 18 and becomes surface reflected light 20. Monitor the normal of the surface of the photodiode 18 with the light 1
The surface reflection light 20 is prevented from returning to the active layer 3 by inclining it by several degrees with respect to 5. When the surface reflected light 20 enters the active layer 3, the output light 21 is affected by the surface reflected light 20, and the noise figure of the output light 21 increases.

[0003]

The semiconductor laser device is required to have a light emitting point position accuracy of ± 50 to 100 μm and an emitting direction accuracy of ± 3 ° with the external package or submount 19. To achieve this accuracy, alignment adjustments between individual components are required. Since the semiconductor laser chip 1 has a size of about 300 μm, it is difficult to adjust the alignment between the semiconductor laser chip 1 and the heat sink 2 or the submount 19, and it is particularly difficult to adjust the angle between them. Further, in the conventional device, it is difficult to reduce the size because individual parts are installed on the submount 19. To meet the demand for miniaturization, it is necessary to miniaturize each component, but if each component is miniaturized, alignment adjustment between each component becomes more difficult. An object of the present invention is to provide a structure of a heat sink that facilitates the angle alignment adjustment with the semiconductor laser chip 1 and enables the size reduction of the semiconductor laser device, and a semiconductor laser device including the heat sink.

[0004]

A first means provided by the present invention for solving the above-mentioned problems is a heat sink on which a semiconductor laser chip is mounted and which dissipates heat received from the semiconductor laser chip. Made of semiconductor material,
A photodiode is formed by incorporating a planar type PN junction surface or PIN structure, and the upper surface side on which the semiconductor laser chip is mounted has a two-step structure having an upper step surface and a lower step surface which are parallel to each other. The interface between the lower surface and the lower surface is a surface inclined with respect to the upper surface and the lower surface, and the PN junction surface or the joint surface of the PIN structure is parallel to the upper surface and the upper surface and Ohmic electrodes are provided only under the inclined surfaces, and ohmic electrodes are respectively formed on at least one of the lower surface facing the upper surface or the lower step surface and the upper step surface, and these ohmic electrodes are the photodiodes. It is characterized by forming the electrode of.

A second means provided by the present invention for solving the above-mentioned problems is to mount a semiconductor laser chip on a heat sink and to partially emit a laser beam from the semiconductor laser chip to a photodiode. In the semiconductor laser device, the output of the semiconductor laser chip is monitored by the output of the photodiode, wherein the heat sink is made of a semiconductor material and has a planar PN junction surface or a PIN structure. The photodiode is formed, and a step structure having two steps is formed on the upper surface side on which the semiconductor laser chip is mounted, the upper step surface and the lower step surface being parallel to each other, and the boundary surface between the upper step surface and the lower step surface is the upper step. Surface and the lower step surface are inclined, and the PN junction surface or the junction surface of the PIN structure is parallel to the upper step surface. Provided only under the upper surface and the inclined surface, and has an ohmic electrode on at least one of the lower surface or the lower surface facing the upper surface and the upper surface, and these ohmic electrodes It is used as an electrode of a diode, and the semiconductor laser chip is mounted on the lower step surface with the monitor light emitting end surface facing the inclined surface and the active layer parallel to the lower step surface.

[0006]

The heat sink of the present invention is made of a semiconductor such as silicon, and a photodiode is formed by incorporating a planar type PN junction surface or PIN structure in this semiconductor. The upper surface side on which the semiconductor laser chip is mounted has a two-step structure, and a PN junction surface or PI
The joint surface of the N structure is provided only below the upper surface and the inclined surface. By adopting such a structure, the photodiode 18 required in the conventional laser device shown in FIG. 6 is not necessary, and the laser device can be downsized. Further, the semiconductor laser chip and the heat sink can be angularly aligned by bringing the monitor light emitting end surface of the semiconductor laser chip into contact with the inclined surface. Therefore, by adopting the heat sink of the present invention, it becomes unnecessary to perform angular alignment between the semiconductor laser chip and the heat sink in the manufacture of the semiconductor laser device (which was a difficult work in the conventional device using the heat sink). When the monitor light emitting end face of the semiconductor laser chip is brought into contact with the inclined surface, the monitor light incident from the inclined surface is refracted to reach the PN junction surface (or PIN structure) and is detected.
Further, the laser light reflected by the inclined surface does not return to the active layer of the semiconductor laser chip, which is the same as the conventional structure shown in FIG.

[0007]

EXAMPLES The present invention will be described in more detail with reference to examples. FIG. 1 is a side view of a semiconductor laser device which is an embodiment of the present invention, FIG. 2 is a plan view of the device, FIG. 3 is a partial side view showing a portion indicated by reference numeral 10 in FIG. 1 in an enlarged manner, and FIG. 1 is a perspective view of the device of FIG. 1, and FIG. 5 is a diagram showing a circuit diagram configured by the device of FIG.

The semiconductor laser device of FIG. 1 comprises a semiconductor laser chip 1 and a heat sink 2. The heat sink 2 is made of a semiconductor material such as silicon, has a built-in planar type PN junction surface 9, and has a two-step structure with an upper surface and a lower surface parallel to each other on the upper surface side on which the semiconductor laser chip 1 is mounted. , The heat sink upper electrode 8 on the upper surface
And a heat sink upper electrode 6 on the lower surface, and the boundary surface between the upper surface and the lower surface is a plane of forward mesa inclination with respect to the upper surface and the lower surface, and the lower surface facing the upper surface. Has a heat sink lower electrode 7.

The heat sink upper electrode 8, the heat sink upper electrode 6 and the heat sink lower electrode 7 are all ohmic electrodes. The PN junction 9 is the heat sink upper electrode 8
And provided only below the inclined surface 14. A planar photodiode having one of the heat sink upper electrode 6 or the heat sink lower electrode 7 and the heat sink upper electrode 8 as an electrode and the PN junction surface 9 as a light detection surface is formed. The heat sink upper electrode 6 forms a bonding pad on which the semiconductor laser chip 1 is mounted. The semiconductor laser chip 1 includes a semiconductor laser upper surface electrode 4 and a semiconductor laser lower surface electrode 5, and when an electric current is passed between these electrodes 4 and 5, the active layer 3 emits light, and the output light 21 is emitted from the front surface and the rear surface. The monitor light 15 is emitted from. In the figure, the rear surface is the monitor light emitting end surface 13
It is shown as.

The monitor light 15 is incident on the inclined surface 14 of the heat sink 2. The inclined surface 14 is a plane of a forward mesa type inclination as shown in the figure. Therefore, the light 17 of the monitor light 15 reflected by the inclined surface 14 forms an angle with the monitor light 15 and does not return to the active layer 3. The light 16 of the monitor light 15 that has entered the heat sink 2 is refracted by the inclined surface 14, reaches the PN junction surface 9, and is converted into a current by the PN junction surface 9. Monitor light 15
Is refracted on the inclined surface 14 as shown in the figure because the refractive index of the semiconductor material such as silicon forming the heat sink 2 is about 3 to 4 times larger than the refractive index of the air or the inert gas in the atmosphere.

The semiconductor laser chip 1 is a rectangular parallelepiped,
The inclined surface 14 is a flat surface. Therefore, the lower side of the monitor light emitting end surface 13 of the semiconductor laser chip 1 is set to the inclined surface 1
4, the semiconductor laser chip 1 is bonded to the heat sink upper electrode 6 so that the optical axis of the semiconductor laser chip 1 (optical axis of the output light 21) and the longitudinal axis of the heat sink 2 (central axis in the longitudinal direction). You can match the direction with. More on this below. Vertical direction (elevation) of the optical axis of the semiconductor laser chip 1
The semiconductor laser chip 1 to the heat sink upper electrode 6
When mounted on the heat sink 2, they are uniquely determined in the longitudinal axis direction of the heat sink 2 (parallel to each other in this embodiment). Further, in the left-right direction (azimuth) of the optical axis of the semiconductor laser chip 1, the lower side of the monitor light emitting end face of the semiconductor laser chip 1 is brought into contact with the inclined surface 14, so that it is unique to the longitudinal direction of the heat sink 2. (Parallel to each other in this embodiment). Therefore, in the present embodiment, the semiconductor laser chip 1 and the heat sink 2 are simply bonded by contacting the semiconductor laser chip 1 on the upper electrode 6 of the heat sink 2 and the monitor light emitting end face 13 to the inclined surface 14 and bonding. Angular alignment is performed.

The circuit diagram of this embodiment is shown in FIG.
It becomes like. In FIG. 5, reference numeral 11 indicates a semiconductor portion of the semiconductor laser chip 1, that is, the semiconductor laser itself, and reference numeral 12 indicates a semiconductor portion forming a photodiode in the heat sink 2 (photodiode itself).
Indicates. FIG. 5A is a circuit diagram of an apparatus in which the electrode 6 (or 7) is used as an anode and the electrodes 4 and 8 are used as cathodes. FIG. 5B is a circuit diagram of the device in which the electrodes 4 and 8 are used as anodes and the electrode 6 (or 7) is used. It is a circuit diagram of the apparatus used as the cathode.

In the present embodiment, as described above, the heat sink 2 has not only the function of dissipating heat but also the function of a photodiode, and the upper surface of the heat sink 2 has a two-step structure. Such a structure is provided by the photodiode 18 and the submount 19 in the conventional example of FIG.
Unnecessary, enabling downsizing of the semiconductor laser device,
In addition, angular alignment between the semiconductor laser chip 1 and the heat sink 2 is made extremely easy.

In the above embodiment, the heat sink 2 has P
Although the N junction 9 is provided, the laser light 16 may be detected by a PIN structure instead of the PN junction 9.

[0015]

As described above in detail with reference to the embodiments, according to the present invention, it is possible to easily adjust the angular alignment with the semiconductor laser chip 1 and to reduce the size of the semiconductor laser device. And the semiconductor laser device provided with this heat sink can be provided.

[Brief description of drawings]

FIG. 1 is a side view of a semiconductor laser device according to an embodiment of the present invention.

FIG. 2 is a plan view of the semiconductor laser device of FIG.

FIG. 3 is a partial side view showing a portion indicated by reference numeral 10 in FIG. 1 in an enlarged manner.

FIG. 4 is a perspective view of the semiconductor laser device of FIG.

5 is a circuit diagram of the semiconductor laser device of FIG.

FIG. 6 is a side view of a conventional semiconductor laser device.

7 is a plan view of the semiconductor laser device of FIG.

[Explanation of symbols]

1 semiconductor laser chip 2 heat sink 3 active layer 4 semiconductor laser upper surface electrode 5 semiconductor laser lower surface electrode 6 heat sink upper electrode (semiconductor laser bonding pad) 7 heat sink lower portion 8 heat sink upper electrode (photodiode upper surface electrode) 9 photodiode PN junction surface 10 Area shown in the figure 11 Semiconductor laser 12 Photodiode 13 Monitor light emitting end face 14 Sloping surface 15 Monitor light 16 Slope transmitted light 17 Slope reflected light 18 Photodiode 19 Submount 20 Surface reflected light 21 Output light

Claims (4)

[Claims] 1. A heat sink for mounting a semiconductor laser chip and dissipating heat received from the semiconductor laser chip, wherein the heat sink is made of a semiconductor material and is a planar type PN junction surface or P.
A photodiode having a built-in IN structure is formed, and the upper surface side on which the semiconductor laser chip is mounted has a two-step structure having an upper step surface and a lower step surface which are parallel to each other, and between the upper step surface and the lower step surface. The boundary surface forms a surface inclined with respect to the upper surface and the lower surface thereof, and the PN junction surface or P
The joining surface of the IN structure is parallel to the upper step surface and is provided only under the upper step surface and the inclined surface, and at least one of the lower surface or the lower step surface facing the upper surface and the upper step surface. A heat sink characterized in that ohmic electrodes are respectively formed on and, and these ohmic electrodes form electrodes of the photodiode. 2. The heat sink according to claim 1, wherein the inclined surface is a plane of a forward mesa type. 3. A semiconductor laser chip is mounted on a heat sink, a part of laser light emitted from the semiconductor laser chip is received by a photodiode, and the output of the semiconductor laser chip is monitored by the output of the photodiode. In the semiconductor laser device described above, the heat sink is made of a semiconductor material and has a planar PN junction surface or a PIN structure to form the photodiode, and upper surface parallel to each other on the upper surface side on which the semiconductor laser chip is mounted. And a lower step surface have a step structure of two steps, and a boundary surface between the upper step surface and the lower step surface is a surface inclined with respect to the upper step surface and the lower step surface, and the PN junction surface or the PIN structure is formed. Provided only below the upper surface and the inclined surface with the joint surface parallel to the upper surface,
The lower surface facing the upper surface or at least one of the lower surface and the upper surface have ohmic electrodes, and these ohmic electrodes are electrodes of the photodiode, and the semiconductor laser chip emits monitor light. A semiconductor laser device, wherein an end face is directed to the inclined surface, and an active layer is mounted on the lower step surface in parallel with the lower step surface. 4. The semiconductor laser device according to claim 3, wherein the inclined surface is a plane of forward mesa type inclination.